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Bought scope and mount - now need eyepieces

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#1 FTLAUDSKY

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Posted 03 February 2013 - 11:29 PM

So after weeks of searching and a *BLEEP* off girlfriend I finally bought my first scope and mount. Man do I feel poor now in both my bank account and compared to most people here. I Spent way more than I wanted, but figured I might as well get quality gear. I went with a William Optics GT81 with the new Advanced VX mount. I now need to know what eyepieces. I bought the 2" WO carbon diagonal, 1.25 GSO barlow, and a 4mm GSO plossl. I was going to add the 6mm, 10MM, and 15mm Plossl's. Whatcha think? I wanted a larger FOV EP, but from reading threads the larger FOV EP's don't match the scope's spec's Please advise!! I am will to spend some money on good EP's, but nothing ridiculous. Recommendations? Cheaper the better I am almost tapped out on the max budget. Was looking at the TV plossl's are they worth it? Thanks

81MM
478MM
F5.9

PS - Scope gets here Tuesday and Mount on Friday. I will post up pictures once I get them.

#2 Thomas Karpf

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Posted 04 February 2013 - 05:44 AM

Nice scope! Congratulations.

As a triplet it will certainly handle high magnification nicely, but smallish refractors excel at low magnification, wide angle views. If you can afford it, the Explore Scientific 30mm 82* eyepiece (currently $249 in sale) will give you AWESOME views of the Milky Way of about 5.3 degrees.

#3 johnnyha

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Posted 04 February 2013 - 06:08 AM

Since you're tapped out I'd suggest getting a 24mm Explore Scientific 68 degree for your widefield eyepiece - $119 - it should also barlow nicely.

#4 Thomas Karpf

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Posted 04 February 2013 - 08:02 AM

A 24mm 68 degree eyepiece provides maximum field of view in a 1.25" eyepiece. So does a 32mm Plossl (50 degree aFOV) or 40mm Plossl (39 degree aFOV).

Simple math: if the focal length x aFOV works out to about 1600, then the eyepiece provides maximum field of view for a 1.25" barrel.
In the 2" size, max FOV is reached when focal length x aFOV is about 2700.

The AstroTech 25mm 1.25" Paradigm Dual ED (70*) is max FOV in 1.25" for $60.
The AstroTech 32mm 1.25" Value Line Plössl is max FOV in 1.25" for $32.
Both are available at Astronomics.

The Agena Astra SWA 38mm 70*,
Astro Tech Tinan Wide Field 70 38mm, and the
University Optics WD70 38mm will all give you max FOV in 2" for $90-99.

Oh, and yes, Televue Plossls are good.

#5 Thomas Karpf

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Posted 04 February 2013 - 09:57 AM

The Agena Astro Enhanced Wide Field eyepieces might be a nice replacement for Plossls for 20mm and below.

http://agenaastro.co...nced wide angle

#6 FTLAUDSKY

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Posted 04 February 2013 - 10:29 AM

Thomas

Where do you get the 1600 and 2700 numbers from? I get the focal length X FOV = max. Just confused how the 1600 and 2700 was calculated. I have read nothing but good things about the ES 68/82 series. Seems like they are best bang for the buck. I plan to get some expensive eyepieces once I can recoup from the initial outlay. Expensive is an understatement after looking at the prices for Ethos, Naglers, etc.

I have a cheap GSO plossl I am going to send back. There is something on the end when I look through it. So what do you recommend? One/two wide FOV EP's and a few Plossl's? Should I buck up and get the televue plossl's or save and get generic and put the $$ in the wide FOV EP's? Seems like a plossl can only be so good at the low focal lengths. I understand the 80mm scope isn't that great for visual, but since its good glass I would think I could get higher magnification (max 180) on a clear night. I would like to buy once cry once, but like saving money if possible. Over time I have no issue buying a nice EP here and there. Just want like 3-4 to start out with that will get me a good range.

#7 howard929

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Posted 04 February 2013 - 10:49 AM

IME when someone doesn't know what they'll like to view, planets, the Moon, doubles, deep space.. etc because this is all a new experience, eyepiece choices vs price can be daunting.

In your instance, I'd recommend an inexpensive (GSO) 8-24 zoom and a 2X barlow. You'd be all in for under $90 with a kit that would be pleasing to use with plenty of time to get your preferences sorted. And if it saves you from making buying decisions now that you may regret later, all the better since the zoom I mentioned is a lot of fun to use.

#8 newtoskies

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Posted 04 February 2013 - 11:09 AM

Nice new scope and welcome to CN and the hobby.
As a newbie to both scopes and the hobby I'd say hold off on any expensive ep. Most experienced members jump the gun and recommend the expensive ep's. Start out with some ep's like tkarpf mentioned above. You already have a 2xbarlow so get a mid and high power ep for now.....and just use the scope.
The most important thing is to learn your scope, viewing and what it is you prefer to view. Then you can go from there and buy the appropriate ep's.
I waited, asked questions and researched before I bought my Paradigm ED 12 and 18m. These work great for what I like to view and have a very nice fov and all stars are pinpoints.

Go for Plossl's mentioned abovein say 30-32mm for low power and 18-20mm for mid power. With these the barlow will give you two extra ep's. OR like Howard siad, an 8-24mm zoom.

Just my 2cents as a newb who went through this and now has ep's he's happy with.

#9 csrlice12

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Posted 04 February 2013 - 11:25 AM

+1 on a cheap zoom. It is great for grabngo, but mostly, it allows you to get a feel for what the various fixed focal length eyepieces will work best for you (which is totally dependent upon your location, eye health, and scope.) Once you find out what f/l eyepieces work for you, then decide how wide-field you want. If you have tracking ability, wide-field may not be as important, unless you're into large nebulous objects like the Veil, then you'll want wide-field. Try out the zoom first though. While I don't use mine much anymore, it's still an eyepiece I keep for quick grabngo, and was indespinsable in helping me early on.

#10 Thomas Karpf

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Posted 04 February 2013 - 12:25 PM

Thomas

Where do you get the 1600 and 2700 numbers from? I get the focal length X FOV = max. Just confused how the 1600 and 2700 was calculated. I have read nothing but good things about the ES 68/82 series. Seems like they are best bang for the buck. I plan to get some expensive eyepieces once I can recoup from the initial outlay. Expensive is an understatement after looking at the prices for Ethos, Naglers, etc.

I have a cheap GSO plossl I am going to send back. There is something on the end when I look through it. So what do you recommend? One/two wide FOV EP's and a few Plossl's? Should I buck up and get the televue plossl's or save and get generic and put the $$ in the wide FOV EP's? Seems like a plossl can only be so good at the low focal lengths. I understand the 80mm scope isn't that great for visual, but since its good glass I would think I could get higher magnification (max 180) on a clear night. I would like to buy once cry once, but like saving money if possible. Over time I have no issue buying a nice EP here and there. Just want like 3-4 to start out with that will get me a good range.


'1600' and '2700' is quick and dirty trigonometry. I KNOW that the 24mm Panoptic, 32mm Plossl and 40mm Plossl have fields of view that are either the maximum for the 1.25" or are close. Similarly, I KNOW that the 41mm Panoptic has maximum field of view for 2", and that the 31mm Nagler is reasonably close.

1600 and 2700 were derived from looking at my Excel file of eyepieces which contains Field of View with my scopes. I sorted the list in descending order by Field of View and looked at the resulting focal length and could easily see the relationship. It's not very accurate, but empirically it works. It gets less accurate as the apparent field of view increases, but it make it relatively easy to compare two eyepieces quickly.

I'm partial to Explore Scientific (ES) eyepieces. They get you 95% of the way to Televue (TV) quality for about half the price. I'm currently saving up for the 30mm ES 82*. I also have the 4.7mm ES82, the 6.7mm ES82, the 14mm ES82, and a 24mm Panoptic. I have a Televue 20mm Plossl that almost never gets used.

If you want to be smart over the long term, here's what I would do:

1) Buy one GOOD eyepiece that gives you maximum (or near maximum) field of view: 41mm TV Panoptic, 31mm TV Nagler, 30mm ES 82*, etc. Note: the 41mm Panoptic will give an exit pupil of about 7mm. As you age, your eyes' abilty to dilate decreases. The 41mm TV Panoptic is usable with your scope, but you will most likely be better off with the 31mm TV Nagler or the 30mm ES82.

2) Buy one GOOD eyepiece that gives you an exit pupil of about 2mm. At this length, the resolution of the scope matches the resolution of your eye. For an f/5.9 scope, that means an eyepiece of 11-12mm. Good quality options include the 12mm TV Delos, the 12mm TV Nagler, the 11mm TV Nagler, the 11mm ES 82*. I still need to fill this hole.

3) Fill in holes in your line. Perhaps something in the 16-24mm length (I bought a 24mm TV Panoptic last year; it's an awesome eyepiece, feather light, and maximum FOV in a 1.25" focuser. The ES 24mm 82* is also getting excellent reviews), and something in the 8-10mm range (perhaps an 8mm TV Delos, or an 8.8mm ES 82, or 9mm TV Nagler).

4) Finally, I would consider one of Televue's zooms. The Televue 3-6mm zoom would be quite nice for high power. If you really wanted to simplify your eyepiece case, a TV 3-6mm zoom and a TV 8-24mm zoom by themselves cover a lot of ground.

I would stay away from Plossls at short focal lengths; the eye lenses are tiny, and eye relief is typically about 75% of the focal length (i.e. a 6mm Plossl focuses 4.5mm from the eyepiece).

#11 FTLAUDSKY

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Posted 05 February 2013 - 10:11 AM

So I was up late last night trying to decide which EP's to buy. I wanted the wow factor out of the gate so I put in an order for the 4.7, 6.6, and 11mm ES 82's. Did I do ok? I was looking at the 100 series as well and figured I will get those next. It's tough since my scope has such a low focal length. Not expecting miracles. I am going to call the store today to see if they are in stock. The lower focal length EP's are impossible to find. I already have a barlow so can't wait. If the EP's are out of stock I'll start with the 100 9mm instead for now. Super excited and will do a report on all the new gear once it gets here. Any other recommendations? Keep em coming and thank you all for your insight.

#12 newtoskies

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Posted 05 February 2013 - 10:49 AM

Good for you. Look forward to your getting them and posting how they are. They are a bit out of my budget but I do plan on getting at least one ES someday.

#13 csrlice12

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Posted 05 February 2013 - 12:07 PM

Your scope is a wide-field scope; and while it will do well at higher powers as it is a ED scope, it's real calling is wide-field. Get a 24 and/or a 30mm widefield like the ES82s (both of these would run you about $350, about 150 for the 24mm and 200 for the 30mm). Because this is also a faster refractor, I'd be leary of cheap widefields.

Fortunately (or unfortunately)you have a top notch fast scope there; and for it to perform to its ability, it's gonna want premium eyepieces. If you ever plan on AP, this will make a nice scope; and then you'll REALLY want premium eyepieces.

#14 REC

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Posted 05 February 2013 - 03:08 PM

I use the ES 6.7mm for high power in my 80mm-ED most nights@80x. I bought 5mm for a jump up to 120x for moon and planets....but the sky has to be prety steady for that combo. Hope your 4.7mm has good views for you. I also have that 11mm and you will like it too. Just FYI...I use my 19 or 20mm in that scope for really nice wide views of star clusters...Had a nice view of M42 the other night with the 6.7mm !!

Have fun and look forward to your observing reports:)

Bob

#15 FTLAUDSKY

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Posted 05 February 2013 - 06:04 PM

Good news - I called the site I ordered the ep's from and they initally said they were out, but got a call back saying they had the 4.7mm and the 11mm. The 6.7mm is still backordered and no time was given other than end of Feb/March. I have made up a spreadsheet with all my magnifications possibilities and I believe I have a decent range - I have a GSO barlow in 1.25 and just bought the 2" model as well. It has the ability to do 1.5X and 2X. The 4.7 and 11 are 1.25's so my magnification levels are as follows - 43, 65, 86 (11mm), 101, 152, 203 (4.7mm). That gives me 5 decent levels - not expecting the 202 to be viable, but maybe on a great sky. I do feel I am missing the lower range under 40X. I am willing to buy one more and opend to suggestings. The 20mm seems too low power (24X)? What do you think. I wouldn't mind going to the 20mm 100. I left room in the lineup for the 100's if I wanted to go that route, but the 9mm is close to the 11mm in magnification level. I am so broke now, but still want more. First it was apeture APO fever (still want a 5-6" who doesn't) and now I have EP fever. I was trying to convince myself to get an Ethos used. I figured I gotta crawl before I walk and held out. I live by the buy once cry once motto. It's alot easier to sell decent gear and get back some money than eat the cost of cheap gear. Thanks again and let me know which wide FOV I should get in the ES line up? Is the 100 worth the extra cash - seem like a deal compared to the 82 higher mm models.

#16 csrlice12

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Posted 05 February 2013 - 07:29 PM

I've been hearing that "another month" for about seven months now.....but it sound like maybe shipments are finally starting to arrive...

#17 REC

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Posted 06 February 2013 - 09:50 AM

Don't forget to keep an eye out on the classified's for alternatives.

#18 FTLAUDSKY

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Posted 06 February 2013 - 11:07 AM

I think I am good on the two EP's to start with, but would like one more larger MM EP. What is the minimum magnification I should be using? The scope has a short FL so I am somewhat limited on how large a FL EP I can use. Also is the 100* series worth the extra cash? Seems like the 82 series is the sweet spot.

On a side note - I recieved my scope yesterday - WOW I am impressed. Had a QC signature with it saying it was inspected before shipment. Very well made, heavy, and love the Blue accents instead of the red. Will do a report with pictures soon. I also got the CF diagonal - very well made and nice to look at. It came with the GT81 field flattner for when I get more into AP. For now though I plan to do visual and enjoy my new toys. Mount will be here Monday and first two EP's next wed. Planning to have a great weekend next week weather permitting. By the way it was partly cloudy last night then turned semi clear by bedtime, but no mount no go.

PS - I monitor the used sites daily (Here, Astromart, and Ebay) - any more I am missing?

#19 Thomas Karpf

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Posted 06 February 2013 - 11:17 AM

Lowest magnification without minimizing the aperture you are using is figured this way:

1) The exit pupil is 7mm (you might want smaller if you're not <30 or so).
2) Eyepiece focal length = Desired exit pupil (7mm in this case) x Focal Ratio of the scope (5.9 in your case) = 41.3mm. The 41mm Panoptic (retail $459) would be a perfect match.

That having been said, the 30mm ES82 gives you 88% of the maximum field of view as the 41 Panoptic, with higher magnification and wider apparent field of view for $299 right now.

#20 FTLAUDSKY

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Posted 06 February 2013 - 12:24 PM

Thomas I sent you PM.

I have another general question - was talking to GF and she wants a Telescope now so we can view together. I was looking at the Twilight II model. How can both telecopes be centered on the same object? I would think that both telescopes would have the object on the inner edges or one in the center and the other off to the side. Am I missing something? As for her scope I am thinking either a larger doublet (ex Lunt 102ED) or mabe a 8" SCT. Haven't decided but would like to use it if possible myself. We have limited space so no Dob/Newt scopes. I can just see my 81 on top of the 102 piggyback or both on the dual mount. Sweet!!! 127/130 would be even better..Just need to convince her to get an APO Triplet....HAHAHAH

#21 Thomas Karpf

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Posted 06 February 2013 - 12:37 PM

For using two scopes at the same time, I'm not familiar with the Twilight II. A quick Google search turned up nothing with regards to finely adjusting the pointing direction of one scope in order to precisely aligh the two scopes. This may not be a problem with wide-angle views, but could be problematic with high power (100x + ?) views.

The options I'm familiar with include:

Universal Astronomics Double-Star ($699 but can hold a 30lb scope on the left and a 40lb scope on the right, and you can collimate the two so they point to the same location at high power.

One of the mounts from http://www.desertsky....com/DSV-2.html with dual-scope option. From what I've read, while motions with the Desert Sky scopes are very smooth, it can be tricky to change eyepieces and not lose your target.

The Desert Sky mount would be cheaper than the DoubleStar, but the DoubleStar handles bigger scopes. That may not be a problem right now, but could be with something bigger like a 5"+ refractor.

#22 Dave Mitsky

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Posted 06 February 2013 - 01:01 PM

I would choose the 30mm Explore Scientific eyepiece over the 41mm Panoptic due to the increased "contrast" created by its higher magnification, as well as its lower cost.

Dave Mitsky

#23 csrlice12

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Posted 06 February 2013 - 01:04 PM

Looking thru the threads, there are numerous side-by-side setupes. Theres a Canadian company that sells a EQ mount specially made for side by side mounting.....

#24 coopman

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Posted 06 February 2013 - 01:09 PM

If you don't have the two scopes carefully balanced on the mount, they can possibly move when you insert or remove an eyepiece if the weight difference between the eyepieces is a lot and the altitude axis is not locked.

#25 Thomas Karpf

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Posted 06 February 2013 - 01:11 PM

As far as side-by-side setups are concerned, using one on an equatorial mount for TWO-PERSON use could be interesting.

When pointed EAST, scope 1 is below scope 2.
When pointed SOUTH, scopes are next to each other.
When pointed WEST, scope 1 is above scope 2.






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